Apparatus for grinding and refinishing crankpins



April 24, 1956 J, A, SILLS 2,742,746

APPARATUS FOR GRINDING AND REFINISHING CRANKPINS Filed April 16, 1952 .'5 Sheets-Sheet l JNVENTOR. Joseph A. Sil/s @M AHys.

J. A. SILLS April 24, 195e APPARATUS FOR GRINDING AND REFINISHING CRANKPINS I5 Sheets-Sheet 2 Filed April 16, 1952 INVENToR. Joseph A. Sil/s BY l @fz QM n Allys.

J. A. SILLS April 24, 1956 APPARATUS FOR GRINDING AND REFINISHING CRANKPINS Filed April 16, 1952 3 Sheets-Sheet 3 [TTS ' INVENTOR. Joseph A. Sil/s United States Patent O APPARATUS FOR GRINDING AND REFIN'ISHING CRANKPINS The present invention relates to-apparatus for grinding and refinishing the crankpins on a crankshaft of an internalV combustion engine withthe crankshaft in its normal position supported by its main bearings in the engine block. Y

Grinding and refinishing devices heretofore proposed for the purpose noted have been of little utility, since they took no account ofthe fundamental requirement in the satisfactory operation of aninternal combustion engine that the crankpin on the crankshaft must not only be smooth vand cylindrical but the axis thereof must be parallel to the axis of the journals on the crankshaft. Now when a crankpin becomes worn or damaged, necessitating regrinding thereof, the outer surface thereof may be rough, elliptical, tapered or attened or the axis thereof may be at-an-angle to or out-of-parallcl with the axis of the journals on the crankshaft. In any case, it is apparent that when the worn crankpin is reground, the grinding device cannot be supported directly upon the damaged crankpin if it is expected that the axis of the reiinished crankpin is to be parallel to the axis of the journals on the crankshaft. Moreover, it has been found that the regrinding of a worn crankpin that is merely rough or scored has a tendency to bring about an out-of-parallel relationship between the axis of the crankpin and the axis of the journals on the crankshaft, when the grinding deviceis supported directly upon the damagedcrankpin during -the regrinding or refinishing operation. Finally,

it will be appreciated that in the cases where the damaged crankpin` is tapered or 'the axis thereofris out-of-parallel relation with the axis of theljournals on the crankshaft, theregrinding of the lcrankshaft with the grinding apparatusfdirectly supported thereupon actually accentuates the out-of-parallel relationship noted. t

I Accordingly, itis a general object of the present inven- Vvtion to provide grinding and refinishing apparatus for the of the damaged crankpin that is undergoing the ,refinishing operation.

t ,-1 Another object ofthe invention is to provide compact .and readily portable apparatus ofthe character noted that may-be driven or operated by any conventional portable drilling or polishing unit of the electric motorpowered type. r j ,A @Another object of the invention is toprovide crankpin grinding apparatus of the character ,described which embodies in the structure thereof, facility gaugeable directly vupon the main bearings of the supported crankshaft insurvv,ingfproperalignment of the apparatus with respect to the axisfofthemain bearings of the crankshaft,

a further. ,-Obiect ,Qfs thel Aitufention 'is' te Pmyidagnltratus of the character noted that is exceedingly flexible and vadaptable with reference to sizes, dimensions and spacings of the various parts of engines so that the crankpins on the crankshafts Vof a wide variety of engines may be readily reground and reiinished thereby, with a minimum interchange of elements in the apparatus, and without removal of the crankshafts from the associated engine blocks.

Still a further object of the invention is to provide apparatus of the type noted that incorporates a minimum number of simple and rugged parts.

Further features of the invention pertain to the particular arrangement of the elements of the crankpin grinding apparatus, whereby the above-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which Figure 1 is a fragmentary perspective view of crankpin grinding and refinishing apparatus embodying the present invention; Fig. 2 is a fragmentary lateral sectional view of the apparatus shown in Fig. l, illustrating the support thereof upon the bottom of an engine block with the crankshaft supported by its main bearings in the engine block; Fig. 3 isa fragmentary longitudinal sectional view of the apparatus, similar to Fig. 2; Fig. 4 is an end elevational view, partly broken away, of a grinding device forming a part of the apparatus illustrated in Figs. l to 3, inclusive; and Fig. 5 is a side elevational view of the grinding device shown in Fig. 4.

, Referring now to Figs. l to 3, inclusive, of the drawings, there is illustrated the block 10 of an internal combustion engine supporting a rotatably mounted crank shaft 11, and grinding apparatus 12 embodying the features of the present invention. vMore particularly, the block 10 is provided with a lower outwardly extending surrounding flange 13 that normally supports an oil pan, not shown, that cooperates therewith to define a crank case housing the crankshaft 11. Also, the block 10 is provided with longitudinally spaced-apart supports 141that r* Nce carry upper bearing elements 15; and the crankshaft 11v is provided with longitudinally spaced-apart journals 16 cooperating with the bearing elements 15, and one or more crankpins 17 (two being illustrated) .disposed between adjacent ones of the journals-16. Of course, ,the supports 14 normally carry lower bearing caps, not shown, in which lower bearing elements are mounted; the upper and lower bearing elements mentioned normally engaging and supporting the journals 16 provided on the crankshaft 11.

In the grinding of one of the crankpins 17 on the crankshaft 11, the `oil pan is rst dropped from the block 10 to expose the crankpins 17 on the crankshaft 11; the crankshaft 11 is then rotated to position the crankpin 17 that is to be ground into its lowermostposition; the associated connecting rod, not shown, is removed from the crankpin 17 mentioned; and the connecting rod mentioned and the associated piston," not shown, is pushed upwardly into the associated cylinder provided in the block 10 so that it is out kof,interfering relation with vthe crankpin 17 mentioned. At this time, the apparatus 12 is assembled upon the bottom of the vblock 10 and secured in place in a manner more fully described hereinafter.

Considering nowvthe construction and arrangement of the apparatus 12, it essentially comprises a cradle including a longitudinally extending beam 18, a laterally extending base 19, and a pair of laterally'spaced-apart substantially L-shaped brackets 2Q.. The central portion of the base 19 is arranged below and in crossing .relation with the central portion of the lbeam 1 8; and these parts are secured together by an arrangement including a bolt 21. More particularly, an elongated longitudinally extending slot 22 is formed through the beam 18, between the upper and lower surfaces thereof; and two laterally spaced-apart elongated longitudinally extending grooves 23 are formed in the upper surface of the beam 18 adjacent to the edges of the slot 22 so as to provide two elongated upwardly facing longitudinally extending shoulders 24 on opposite sides of the slot 22. The bolt 21 is arranged in the slot 22 and is provided with an upper squared head 25, the opposite sides of which are dis posed in the grooves 23, and the opposite unoersides of which engage the shoulders 24. The lower end of the bolt 21 extends through a centrally disposed laterally extending slot Z6 formed in the base 19 and receives on the lower end thereof, a washer 27 that is secured in place by an associated wing nut 28.

Each of the brackets includes an upstanding leg 29 and a longitudinally extending leg 38; and the opposite ends of the base 19 has slots 31 formed therein that 2- respcctively receive the ends of the upstanding legs 29 of the brackets 28. The lower ends of the legs 29 are slotted. as indicated at 32; and the opposite ends of the base .t9 are slotted, as indicated at 33, so that the relative positions of the legs 29 within the slots 31 formed in the base 19 may be adjusted in two directions, for a purpose more fully explained hereinafter; and each of the legs 29 and the associated end of the base 19 are secured in place by an arrangement including a bolt 34 extending rthrough the slots 32 and 33 that carries on the outer end thereof a washer 35 that is secured in place by a wing nut 36. The legs 3) of the brackets 20 engage the undersurface of thc surrounding flange 13 carried on the bottom of the block 10 and are secured in place by an arrangement including a plurality of bolts 37 extending through slots 38 formed in the legs 3f), the upper ends of the bolts 38 extending through holes provided in the flange 13 and receiving nuts 39.

Two longitudinally spaced-apart aligning blocks 40 are respectively carried by the opposite ends of the beam 18 and removably secured in place by stops 41 respectively secured to the opposite ends of the beam 18 by associated screws 42. The aligning blocks 40 are adjustable in the longitudinal direction toward and away from each other; and are also adjustable in the vertical direction toward and away from the beam 18. More specically, each of the aligning blocks 40 comprises a body 43 substantially rectangular in plan, the upper end of the body 43 having a substantially V-shaped notch 44 formed therein that is adapted to receive and engage one l of the journals 16 on the crankshaft 11, and the lower end of the body 43 having a slot 45 formed therein providing two laterally spaced-apart legs 46 straddling the beam 18. The lower ends of the legs 46 are bridged by an attached plate 47 disposed below the beam 18; and a guide block 48 that is substantially H-shaped is arranged between the legs 46 above the beam 18. Finally, a compression spring 49 is arranged between the bottom of the slot and the top of the guide block 48, the bottom of the guide block 48 engaging the top of the beam 18. Thus it will be understood that in each aligning block 40, the compression spring 49 urges the upper end of the body 43 upwardly away from the beam 18 causing the V-shaped notch 44 to be urged into engagement with the associated journal 16 on the crankshaft 11.

Finally, the apparatus 12 comprises a grinding device 50 disposed in grinding relation with the crankpin 17 on the crankshaft 11 that is to be reground or refinished, the grinding device 50 being detaehably secured to the beam 18, in a manner more fully described hereinafter. The grinding device 50 may be fundamentally of a known construction, but preferably it is constructed and arranged in the manner illustrated in Figs. 4 and 5. Specifically, as illustrated, the grinding device 5t) comprises a supporting frame or housing 51 of the split-type and including substantially complementary sections 52 and 53, the housing sections 52 and 53 being detachably secured together by an arrangementincluding two outwardly projecting studs 54 anchored in holes provided in the housing section 52 and extending through aligned holes provided in the housing section 53, the outer ends of the studs 54 being threaded and receiving cooperating threaded caps 55. Also, the grinding device 50 comprises a grinding element 56 of the split-ring type and including substantially complementary ring sections 57 rotatably mounted in assembled relation within the housing 51, the outer surfaces of the ring sections 57 carrying teeth providing a continuous worm gear 58 about the outer surface of the grinding element 56. Two substantially complementary semi-cylindrical grinding shoes 68 are respectively carried by the inner surfaces of the ring sections 57 of the grinding clement 56, the shoes 60 being secured in place by pairs of set screws 62 threaded in longitudinally spaced-apart tapped holes respectively formed in the ring sections 57. The inner end of cach of the set screws 62 is provided with a projection 63 that is received in a cooperating recess provided in the outer surface of the associated shoe 60; and the outer end of each of the set screws 62 is provided with a squared recess 64 that is adapted to be brought into alignment with respect to an associated hole 65formed in the housing section 53, so that each of the set screws 62 is accessible through the associated hole 65 by a squareended key, not shown. Finally, each of the shoes 60 carries a cooperating segmental grinding pad 66 that directly engages the adjacent outer surface of the crankpin 17 on the crankshaft 11.

For the purpose of rotating the grinding element 56 a worm 67 carried by a rotatably mounted shaft 68 is arranged in a subhousing 69 removably secured to the housing section 52, the worm 67 meshing with the worm gear 58 disposed about the outer surface of the grinding element 56. The lower end of the shaft 68 terminates in a ball xture 70 carrying a pair of outwardly directed pins 71, that are, in turn, received in a quickdetachable fixture 72 having cooperating pairs of substantially inverted T-shaped slots 73 formed therein. The lower end of the xture 72 is provided with a squared shank 74 that is adapted to be chucked in the chuck of a drilling or polishing unit of the electric motor driven type.

In view of the above description of the grinding device 50, it will be understood that when the shank 74 of the fixture 72 is chucked in a motor unit of the type noted that the grinding device 50 may be readily operated, the fixtures 70 and 72 being readily attachable and detachable with respect to each other. More particularly, when the motor unit mentioned is operated, the shaft 68 is rotated effecting rotation of the worm 67 and the consequent rotation of the grinding element 56, whereby the grinding shoes 60 are rotated effecting rotation of the grinding pads 66 directly engaging the outer surface of the crankpin 17 on the crankshaft 11. Of course, the grinding pads 66 carried by the grinding shoes 60 are essentially formed of Carborundum, or the like, to carry out the grinding action upon the outer surface of the crankpin 17.

Finally, the lower end of the housing section 52 carries a downwardly extending squared shank 75 that terminates therebelow in a threaded stud 76. The grinding device 50 is supported by the beam 18, the stud 76 projecting through the slot 22 formed therein and the squared shank 75 being received between the two laterally spacedapart grooves 23. Finally, the grinding device 50 is rigidly secured in place by a nut 77 that is received by the outer end of the stud-76, the nut 77 engaging the lower surface of the beam 18.

Considering now the overall operation of the apparatus 12, after the oil pan, not shown, has been removed from the bottom of the `engine block 10 and the erankpin 17 75 that is to be refinished is brought into its lowerrnost posi- `crankshaft 11.

the total amount of grinding to '5 tion, and the bearing caps, not shown, have been removed from the adjacent journals 16 on rthe crankshaft 11, the grinding device 50 is assembled vupon the exposed crankpin 17 that is to be retini'shed. More particularly, Athe split construction of the housing 51V 'and the Vsplit-'ring construction of the grinding element 56 and` of the grinding shoes 60 accommodate ready assembly of the grinding device 50, as a whole, upon the -exposed crankpin 17; and the threaded caps 55 retain the component parts of the grinding device in assembled relation. The cradle structure of the apparatus 12 is then brought in place with respect to the bottom of the engine block 10, the legs 30 of the .brackets 20 being rigidly secured in place upon the opposite sides of the flange 13 by the cooperating bolts.37 and nuts 39. The wing nuts 28 and. 36 are loose at this time; and the stud 76 is passed through the slot 22 providing in the beam 18, the squared shank -75- being received in the laterally spaced-apart grooves 23 formed in the beam 18. At this time, the base 19 and the beam18 are lifted with respect to the brackets 20 sothat the yaligning blocks 40 are brought into gauging relation with respect to the adjacent journalsy 16 on the, crankshaft 11, the V-shaped notches 44 straddling the outer surfaces of the journals 16` mentioned in order to insure .alignment of the cradle, as a whole, with respect to the journals 16 and consequently with the axis thereof. When the cradle, as a whole, is thus aligned withrespect to the axis of the journalsV 16, the wing'nuts 28 and 36 are respect to the beam 18 accommodates different longitudinal spacings of thev journals. 16 on dijerent crankshafts 11. .The vertical adjustment of the aligning blocks 40 with respecttothe beam 18 accommodates diierent offset distances between the axis of the journals 16 and the axis of the crankpins. 17. on different crankshafts 11; while the adjustment of the grinding device 50 longitudinally of the beam 18 accommodates different spacings ofthe crankpins 17 with respect to the adjacent journals 16 on different crankshafts 11.

Further, it will be understood that the grinding shoes 60 that are supportedv by the ring sections 57 of the grindingelement 56 may be of different thicknesses inorder to tightened so as firmly to lock the base 19 in place with t respect to` the brackets 20 and to lock the beam 18 in place with respect to the base 19. At this time, the nut 77 isplaced upon the stud 76 in-order rigidly to secure the grinding device 50 in place with respect to the beam 18 and so that the main axis of the grinding device 50 is in parallel relation with respect tothe axis of the journals 16 of the crankshaft 11. Now, the-motor unit is attached vto the grinding device 50 and the first pair of set screws-62 are lrotated into alignment with respect to .the openings 65 formed in the housing section 53 so that the associated key, not shown, maybe employed for the purpose of setting the associated grinding shoes 60 in order to bring the associated grinding pad 66 intofirm engagement with the adjacent outer surface of the crankpin 17 on the In a similar manner, the other of the grinding shoes 60 is set, whereby the two grinding. pads `66 engage the opposite sides of the outer surface of the exposed crankpin 17. At this time, operation of the motor unit brings about the desired'rotation of the grinding element 56 and the consequentgrinding of .the outer Asurface of .the'crankpin 17 by the grinding pads A66.A After some initialv grinding'of the crankpin 17,v the set screws v62 may be retightened in order appropriately yto govern whichthe crankpin 17 is ultimately subjected.v l Reconsidering the construction of the grinding device v50, it will be appreciated that the set screws 62 carried by each of the ring sections 57 of the grinding element 56 is independently adjustable so .that-k any original taper of the crankpin 17 may be eliminated therefrom. vSpeciiically, by adjustment of the pairs of set screws 62, -the axis of the associated grinding shoes 60 may be positioned at an angle to the main axis of the grinding device 50 so as to accommodate disproportional grinding of one end of the crankpin 17 vfor the- .purpose of f eliminating the taper, previously mentioned. Y'Rec'onsidering the cradle structure, as a whole, it will be appreciated that the flexibilityv of adjustment of the component parts thereof lrenders the' apparatus 12 readily adaptable to the grind- `ing of the crankpins on the crankshafts of a large vvariety of internal combustion engines, notwithstanding the accommodate different outer diameters of the different crankpins 57; Moreover, diierent ones of the grinding pads 66 may be of diilerentcoarseness of abrasion for the purpose of taking respective rough and fine abrasive cuts upon the associated crankpin 17 l v'lecapitulatingin the assembly of the apparatus y12, it will be understood that since the aligning blocks 40 are brought directly into engagement with the adjacent main bearings 16 of the crankshaft 11, the position of the cradle structureof the apparatus 12 is always properly aligned with respect 'to the axis of the journals 16 of the crankshaft 11; which position of alignment of the cradle structure is secured and maintained when the various component elements thereof are locked in place employing the various I wing nuts 28 andf36. Moreover, since the given position of the grinding device 50 is fixed and established with respect to the aligned position of the beam 18, itfollows that the main axis of the grinding device 50 is always' :properly aligned with respect to. the axis of the journals 16 on the crankshaft 11, whereby any initial lack of parallelism between the axis of the journals '16 and the axis o f thecrankpin 17 is eliminated incident to the grinding operation of the grinding device 50, so that at the conclusion of the grinding operation, the parallelism between the axis of the journals 16 and the axis of the crankpin17 has beenV established along with the renisli of the outer 's'iirface of the' crankpin 17 to a smooth and cylindrical condition of a predetermined and desired diameter.

In-view of the foregoing,.it is apparent that there has been rprovided improved, iexible and portable apparatus forv grinding and refinishing the crankpins on a crankshaft vof an internal combustion engine with the crankshaft in itsnormal position supported by its main bearings in the engine block, wherein the apparatus in its operation not only returns the outer surface of the crankpin ,to a smooth and cylindrical condition, but also restores parallelism between the axis of the journals an the axis of the crankpin on the crankshaft. A

While there has been described what is at present considered tobe the preferred embodiment of the invention, it will be understood that various modiiications'may be made therein, and it is intended to cover in the appended claims all such modifications `as fall within the true spirit and 'scope of the invention. p What is claimed is:

n combination with an engine block provided with ua number of main bearings supporting a crankshaft at a corresponding number or" journals provided thereon; grinding apparatus comprising a longitudinally extending cradle disposed below said crankshaft, means includinga ypair of upstandingspaced-apart aligning blocks carried by, said cradle and cooperating with a longitudinally spaced-apart pair of said journals disposed on opposite sides of a crankpin also provided on said crankshaft for ,locating said cradle in a predetermined position of fixed alignment with respect to the center line of said pair of journals, means for securing said cradle to isaid block in said predetermined position with the upper ends of said pair of aligning blocks in rm engagement-with said pair of journals, and a grinding device carried by said cradle and arranged in grinding relation with said crankpin.

2. In combination with an engine block provided with a number of main bearings supporting a crankshaft at a corresponding number of journals provided thereon; grinding apparatus comprising a longitudinally extending cradle disposed below said crankshaft, means including a pair of upstanding longitudinally spaced-apart aligning blocks carried by said cradle and cooperating with a longitudinally spaced-apart pair of said journals disposed on opposite sides of a crankpin also provided 0n said crankshaft for locating said cradle in a predetermined position of fixed alignment with respect to the center line of said pair of journals, means for securing said cradle to said block in said predetermined position with the upper end of said pair of aligning blocks in rm engagement with said pair of journals, a grinding device carried by said cradle and arranged in grinding relation with said crankpin on said crankshaft, and means including cooperating parts respectively carried by said cradle and by said grinding device for securing said grinding device in a given position with respect to said cradle and in xed alignment with respect to the center line of said pair of journals.

`3. The combination set forth in claim 2, wherein said grinding device includes a stationary frame secured to said cradle, and a grindingelement rotatably mounted upon said frame and surrounding said crankpin, the center line of said grinding element being parallel to and in offset relation with the center line of said pair of journals.

4. The combination set forth in claim 3, wherein said grinding element is essentially in the form of a split ring including a pair of complementary parts, and further includes a pair of grinding shoes respectively cam'ed by said ring parts and engaging the opposite sides of said crankpin.

5. The combination set forth in claim 4, and further comprising means for adjusting the angle between each of said grinding shoes and the corresponding one of said ring parts so as to accommodate adjustment of the angles between said grinding shoes and the center line of said crankpin to facilitate the grinding of any initial taper from said crankpin.

6. The grinding apparatus set forth in claim 3, and further comprising a shaft rotatably mounted upon said frame for rotating said grinding element, and a quickdetachable drive fixture carried by said shaft.

7. In combination with an engine block provided with a number of main bearings supporting a crankshaft at a corresponding number of journals provided thereon; grinding apparatus comprising a cradle disposed below said crankshaft and including a longitudinally extending beam, means including a pair of upstanding longitudinally spaced-apart aliging blocks carried by said beam and cooperating with a longitudinally spaced-apart pair of said journals disposed on opposite sides of a crankpin also provided on said crankshaft for locating said cradle in a predetermined position of fixed longitudinal alignment with respect to the center line of said pair of journals, means for securing said cradle to said engine block in said predetermined position with the upper ends of said pair of aligning blocks in firm engagement with said pair of journals, a grinding device carried by said cradle and including a rotatably mounted grinding element surrounding and in grinding relation with said crankpin, and means including cooperating parts respectively carried by said cradle and by said grinding device for securing said grinding device in a given position with respect to said cradle so that the center line of said grinding element is parallel to and in olset relation with the center line of said pair of journals.

8. The combination set forth in claim 7, wherein said aligning blocks carried by said beam are slidably mounted thereon for movement and consequent adjustment in the vertical direction with respect thereto so as to accommodate initial adjustment of said grinding element toward and away from the center line of said pair of journals dependent upon the offset of the center line of said crankpin with respect to the center line of said pair of journals.

9. The combination set forth in claim 8, and further comprising compression springs respectively arranged betweensaid aligning blocks and said beam and biasing the outer ends of said aligning blocks in the vertical direction away from said beam.

10. The combination set forth in claim 7, wherein said aligning blocks carried by said beam are slidably mounted thereon for movement and consequent adjustment in the longitudinal direction with respect thereto so as to accommodate initial adjustment of the longitudinal spacing therebetween dependent upon the longitudinal spacing between said pair of journals.

l1. The combination set forth in claim 7, wherein said grinding device carried by said cradle is slidably mount ed thereon for movements and consequent adjustment in the longitudinal direction along said beam so as to accommodate initial adjustment of the longitudinal position thereof dependent upon the longitudinal position of said crankpin between said pair of journals.

l2. The combinationset forth in claim 7, wherein said means for securing said cradle to said engine block in said predetermined position includes a pair of laterally spaced-apart brackets respectively secured to the opposite sides of the bottom of said engine block.

13. The combination set forth in claim 7, wherein said cradle also includes a laterally extending base secured to said beam, and wherein said means for securing said cradle to said engine block in said predetermined position includes a pair of laterally spaced-apart brackets respectively secured to the opposite ends of said base and to the opposite sides of the bottom of said engine block.

14. The combination set forth in claim 13, wherein said brackets are adjustably secured to the opposite ends of said base to accommodate initial lateral adjustment of said brackets dependent upon the width of said engine blockl between the opposite sides thereof.

15. The combination set forth in claim 13, wherein said brackets are adjustably secured to the opposite ends of said base to accommodate initial vertical adjustment of said cradle dependent upon the offset of the center line of said crankpin with respect to the center line of said pair of journals.

16. The combination set forth in claim 7, wherein said cooperating parts respectively carried by said cradle and by said grinding device for securing said grinding device in said given position with respect to said cradle take the form of a longitudinally extending slot formed in said beam and a squared shank carried by said grinding device and slidably received in said slot so as to accommodate initial adjustment of the longitudinal position of said grinding device along said beam dependent upon the longitudinal position of said crankpin between said pair of journals.

17. The combination set forth in claim 7, wherein said aligning blocks have longitudinally aligned substantially V-shaped notches respectively formed in the outer ends thereof and arranged respectively to receive and to vengage respective ones of said pair of journals.

References Cited in thc le of this patent UNITED STATES PATENTS `1,967,744 Craft July 24, 1934 2,179,465 Blazek Nov. 7, 1939 2,201,664 Ferguson May 2l, 1940 2,289,694 Blazek et al. July 14, 1942 2,519,087 Tydeman Aug. 15, 1950 

